I just picked up 2 more Sage extenders and as long as you're satisfied with the UI as is, it's the easiest thing in the world.
Just picked up an el cheapo TV for the bedroom (btw great deal. Dynex 42" LCD 1080P for $649) and because I only needed to run the audio through the TV setting up the Sage extender was easier than setting up a DVD player.
I did have to upgrade to a Gigabit switch. My home network is soon going to need a full time lan admin. In a moment of providence the same night I said I needed to upgrade to the switch Dell had a killer 24 hour deal on the Trendnet Greennet switches.